Electronic system for monitoring clutch brake engagement and clutch slippage

Abstract

An electronic system for monitoring the operation of a vehicle friction clutch assembly and for generating an indication when the clutch brake of the assembly is frictionally engaged is disclosed. The system generates an electrical signal which is representative of the rotational speed of the clutch brake. To accomplish this, a plurality of magnets or a plurality of radially outwardly extending teeth are secured to the clutch brake. A sensor is disposed near the clutch brake which is responsive to the passage of the magnets and teeth rotating thereby. The sensor generates an electrical pulse train signal having a frequency which is proportional to the rotational speed of the clutch brake. An electronic control circuit is provided for generating an indication when the value of the clutch brake rotational speed signal approaches zero, indicating that the clutch brake is frictionally engaged. A similar sensor be provided for determining the rotational speed of the flywheel of the friction clutch assembly. The control circuit compares the flywheel rotational speed signal with the clutch brake rotational speed signal and generates an indication when the values of the two signals are not equal or when they differ by more than a predetermined amount. Such a situation would occur when there is slippage in the friction clutch assembly which requires maintenance. The flywheel rotational speed signal can also be displayed separately as an analog or digital representation of the engine speed.

What is claimed is: 
     
       1. In a friction clutch assembly including a rotatable input member, a rotatable output member, means for selectively connecting the input member to the output member for rotation therewith, and clutch brake means connected for rotation with the output member for selectively slowing the rotational speed of the output member, a system for generating an indication when the rotational speed of the clutch brake means is less than a predetermined minimum rotational speed comprising: means for generating a signal which is representative of the rotational speed of the clutch brake means;   means for generating a signal which is representative of the predetermined minimum rotational speed; and   means responsive to said clutch brake means rotational speed signal and said predetermined minimum rotational speed signal for generating an indication when said clutch brake means rotational speed is less than said predetermined minimum rotational speed.   
     
     
       2. The invention defined in claim 1 wherein said means for generating a signal which is representative of the rotational speed of the clutch brake means generates an electrical signal at a frequency which is proportional to the rotational speed of the clutch brake means. 
     
     
       3. The invention defined in claim 2 further including first pulse amplifier means responsive to said electrical signal for generating first output pulses at a frequency which is proportional to the frequency of said electrical signal, each of said first output pulses having a predetermined time duration. 
     
     
       4. The invention defined in claim 3 further including means responsive to said first output pulses for generating second output pulses, each of said second output pulses having a predetermined time duration, the beginning of each of said second output pulses being delayed in time from the beginning of each of said first output pulses by a predetermined amount. 
     
     
       5. The invention defined in claim 4 wherein said means for generating said second output pulses includes inverter means for inverting the magnitude of said first output pulses means and second pulse amplifier means connected to said inverter means, said second pulse amplifier means being responsive to the termination of said inverted first output pulses for generating said second output pulses. 
     
     
       6. The invention defined in claim 5 further including first monostable multivibrator means responsive to said second output pulses for generating an output signal, said output signal being a continuous output signal when the clutch brake means is rotating faster than said minimum rotational speed of the clutch brake means and being a pulsating output signal when the clutch brake means is rotating slower than said minimum rotational speed of the clutch brake means. 
     
     
       7. The invention defined in claim 6 wherein said first monostable multivibrator means defines an internal re-charging rate which is proportional to said predetermined minimum rotational speed of the clutch brake means, said output signal being a continuous output signal when said second pulses are generated at a rate which is faster than said re-charging rate and generates a pulsating output signal when said second pulses are generated at a rate which is slower than said re-charging rate. 
     
     
       8. The invention defined in claim 6 further including gate means for generating an output signal when said first output pulses from said first pulse amplifier means and said output signal from said first monostable multivibrator means are generated simultaneously. 
     
     
       9. The invention defined in claim 8 further including second monostable multivibrator means responsive to said gate means output signal for generating an output signal, said output signal being a continuous first output signal when the clutch brake means is rotating faster than said minimum rotational speed of the clutch brake means and being a continuous second output signal when the clutch brake means is rotating slower than said minimum rotational speed of the clutch brake means. 
     
     
       10. The invention defined in claim 9 wherein said second monostable multivibrator means defines an internal re-charging rate which is proportional to said predetermined minimum rotational speed of the clutch brake means. 
     
     
       11. A friction clutch assembly comprising: a housing;   a rotatable input member;   a rotatable output member;   means for selectively connecting said input member to said output member for rotation therewith including a movable release bearing;   clutch brake means connected for rotation with the output member and axially movable therealong, said clutch brake means adapted to be selectively frictionally engaged between said housing and said release bearing;   means for generating a signal which is representative of the rotational speed of said clutch brake means;   means for generating a signal which is representative of a predetermined rotational speed for said clutch brake means; and   means responsive to said clutch brake means rotational speed signal and said predetermined rotational speed signal for generating an indication when said clutch brake means rotational speed is less than said predetermined rotational speed.   
     
     
       12. The invention defined in claim 11 wherein said means for generating a signal which is representative of the rotational speed of the clutch brake means includes a plurality of projections formed on the clutch brake means and sensor means disposed in the clutch assembly responsive to passage of said projections thereby when the clutch brake means is rotated for generating an electrical signal which is representative of the rotational speed of the clutch brake means. 
     
     
       13. The invention defined in claim 11 wherein said means for generating a signal which is representative of the rotational speed of the clutch brake means includes a plurality of magnets secured to the clutch brake means and sensor means disposed in the clutch assembly responsive to passage of said magnets thereby when the clutch brake means is rotated for generating an electrical signal which is representative of the rotational speed of the clutch brake means.